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motion detector alarm circuit

Motion Detector Alarm Circuit

This motion detector alarm can detect a moving person from a distance of 1 meter. It uses a dual IR Transmitter-Receiver module HOA1405. When the sensor detects the reflected IR rays, alarm will sound for 2 minutes. The circuit can be modified for various applications including AC operated alarm systems.

Schematic of the Motion Detector Circuit

motion detector alarm circuit

IR Dual Reflective Sensors

The main element in the movement detector circuit is the dual IR reflective sensor HOA1405. It has a built in IR diode and an NPN Photo transistor. The black covering of the module filters visible light rays and allow IR rays to fall on the Photo transistor.

When the Photo transistor receives IR rays, it conducts. The collector of the Photo transistor is connected to the trigger pin2 of a short duration Monostable timer built around IC NE 555.

With the given values of R4 and C2, output of IC1 remains high for two minutes to light LED and to activate the buzzer. In the standby state, the photo transistor inside the Dual Reflector module remains non conducting since its base is not getting IR rays.

When a person comes in front of the module, the reflected IR rays will trigger the Photo transistor and its Collector goes to ground potential.
This triggers the Monostable and Alarm sounds.

45 Comments

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  • Abhishek

    Yes it works!!

  • anurag singh

    Can i implement a electronic map for any organization or a college campus by using it’s data base of that organization?????
    Plzzz give me some suggations….idea to implement it…..

  • sunny sharma

    all fine

  • Darius Isanke

    Does NOR LATCH CIRCUIT work with this system or the NAND LATCH CIRCUIT.

  • farah

    what software that have the component of HOA1405?can you reply it as soon as possible..

  • rohan

    can i use a pir motion sensor instead of the dual reflective sensor using the same diagram above

  • Manalef

    stupid ass circuit….its a bullshit….can detect the length of 1 meter my ass….

  • Arshavin

    so your saying the maximum sensitivity of this sensor is 5mm?? any ways to solve this???

  • Jim Keith

    The article states up to 1M, but the spec sheet indicates peak response at 5mm. I have experimented with these sensors and know from experience that even 100mm is wishful thinking.

    The HOA1405 assembly is pre-focused and angled for optimum 5mm sensitivity. Better range may be obtained via using discrete emitter and photo-transistor (narrow angle) components so that they may be focused at a more distant surface. The nature of the surface is also an issue in order to reflect back a reasonable amount of light. Also, a visible light filter is necessary so that ambient light does not interfere with the photo-transistor. Some photo-transistors have integral filters.

  • Arshavin

    can this circuit be added with a dc motor…so that when the sensor triggers, it activates a motor???

    • Jim Keith

      Yes, it may be modified so that it can drive a motor, but first get it working as is before going this far. Also check out my other comment on range.

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